1. Field of the Invention
This invention relates to a light beam projecting device for an auto-focusing camera, and more particularly to a device for projecting a light spot on an object to be photographed so that the auto-focusing device incorporated in the camera may be able to conduct the automatic focus adjustment with the information from the object having sufficient brightness at least at a part thereof to which the focus adjustment should be made.
2. Description of the Prior Art
An automatic focus adjustment has been known in the art. Among various types of the auto-focusing device for a photographic camera, it is advantageous from the viewpoint of economy and compactness to utilize a photoelectric conversion element to receive information from the object to be photographed. In the electrical type of auto-focusing device as above, the output of the photo-electric conversion element or a photodetector is processed through an electric signal processing circuits. This is advantageous in that the structure is not mechanically complicated and accordingly is easy to manufacture and in that the device is able to have high accuracy and compactness in size.
On the other hand, however, the auto-focusing device like this has a defect in that the automatic focus adjustment cannot be conducted when the object to be photographed has insufficient brightness or contrast.